| *Parasites Honey Bee Tracheal Mite (Acarapis woodi) - (also see Malady Info Overview - Trachial Mite)  Acarapis
woodi, the honey bee tracheal mite, infests adult honey bees. This internal parasitic mite lives within the
tracheae, or breathing tubes, inside the thorax of adult honey bees. Mites also may be found in air sacs in the
thorax, abdomen, and head. The mites pierce the breathing tube walls with their mouth parts and feed on the hemolymph,
or blood, of the bees. As a result of mite feeding, the hemolymph of infested bees has a higher than normal bacterial
count. This disease shortens the lives of adult bees, affects flight efficiency and causes a large number of crawling
bees that are unable to fly. As mite populations increase, colony populations dwindle and this can ultimately result
in the death of the colony. Colonies are most affected during winter confinement and early spring like a stress
disease. Mite infestations are at a maximum in the late winter and early spring when the population is composed
of primarily older bees. The honey bee tracheal mite is difficult to identify and study because of its small size;
the female measures 143 to 174 microns long, the male 125 to 136 microns long (no bigger than a dust speck). The
body is oval, widest between the second and third pairs of legs, and whitish in color with a smooth cuticle. A
few long, fine hairs are present on the body and legs. It has long, beak-like mouth parts for piercing the trachea. |
Life Cycle The entire life cycle
of this mite is spent within the respiratory (tracheal) system of the honey bee, except for brief migratory periods.
Within 24 hours after worker bees emerge from their cells as new adults, female mites collect within their tracheae,
where the microscopic mite feeds and reproduces. Each female mite lays five to seven eggs, which require 3 to 4
days to hatch. Male and female mites develop from egg to adult in approximately 11 to 15 days. Eggs hatch into
six-legged larvae, then molt to a non-feeding or pharate nymph stage, and then finally molt to the adult stage.
All stages of the mite—eggs, larvae, pharate adults, and adults—may be found in the tracheae of older bees. Tracheal
mites are spread within colonies as a result of bee-to-bee contact. Only adult female mites emerge from the tracheae
through spiracles (openings to the outside) and attach themselves to the tip of the bee's hair. As bees come in
contact with one another, the mites attach themselves to the body hairs of a passing bee and enter the tracheae
through the spiracles. Bees less than 4 days old are the most susceptible. Bees drifting between colonies can spread
tracheal mites to other colonies. |
Diagnosis and Symptoms  Positive
identification of tracheal mites can be done only by dissection and microscopic examination of honey bee thoracic
tracheae. The tracheae of uninfested bees are clear and colorless or pale amber in color (healthy). In a slight
infestation, one or both tracheal tubes contain a few adult mites and eggs, which may be detected near the spiracular
openings. At this stage, the infested tracheae may appear clear, cloudy, or slightly discolored. Infested tracheae
undergo progressive deterioration and show patchy discoloration. The tracheae of severely-infested bees have brown
blotches with brown scabs or crust-like lesions, or may appear completely black, and are obstructed by numerous
mites in different stages of development. Feeding by the mites damages the walls of the tracheae. The bee's flight
muscles (in the thorax) may also become atrophied in severe infestations. The lives of adult bees are shortened
and their flight efficiency and perhaps thermoregulatory ability are also affected. As mite populations increase,
colony populations dwindle, which ultimately can lead to the death of the colony. Many infested colonies die in
late winter or early spring. Colonies killed by tracheal mites during the winter typically have plenty of stored
honey remaining and a small cluster of dead bees. However, severely infested colonies also can die during the spring,
summer, or fall. When a colony is near death, large numbers of bees may be seen crawling out of the hive unable
to fly. These bees may display abnormally positioned wings that look disjointed ("K" wings) and may be
trembling, symptoms that can result from diseases associated with the tracheal mites. |
Treatment Tracheal mite populations
should be reduced in the fall to aid colonies in overwintering. Menthol is officially registered in the United
States for the control of the honey bee tracheal mite in overwintering honey bee colonies. Before applying menthol
or any chemical to a bee hive, remove all surplus honey for human consumption. If treating with menthol in the
autumn, leave honey for winter stores on the colony during treatment. Reduce the colony to its wintering size (approximately
two deep hive bodies) and remove any empty supers or additional equipment, then treat with menthol.Menthol treatment consists of approximately 1/3 cup of menthol pellets or crystals. For the best vaporization, we recommend that you place the menthol in 7-by-7-inch packets made of window screen or a material with a similar large mesh. One menthol packet will treat one honey bee colony. It is important that all colonies in an apiary receive mite treatment at the same time. Untreated colonies serve as nearby sources for mite reinfestation and reduce mite treatment effectiveness. Menthol treatment for tracheal mite control and Apistan treatment for varroa mite control may be applied to honey bee colonies at the same time. Apply menthol when mean daily temperatures (add daily high and low, then divide by 2) are expected to be 65°F or higher for at least the next 10 to 14 consecutive days; optimum treatment times for most of Pennsylvania occur in September. Place the menthol packet as close as possible to the top of the broodnest. Ideally, it should be underneath the winter stores and above the winter cluster. If the weather is expected to be cool to moderate, place the packet on the center of the top bars. If hot weather (above 80°F) is expected for several days, place the packet on the bottom board and remove any entrance reducers. Leave the menthol in the colony for 4 to 6 weeks after application. At the end of this time, and before wintering, remove the packets. Store any remaining menthol in a plastic container in the freezer for reuse next year. If more than half of the original amount of menthol remains in a packet, it is unlikely that the colony received an effective treatment. |
Grease Patties  Grease
patty treatments may be a better option for treating colonies in climates where the environmental conditions are
not met. Patties are made from a mixture of one part vegetable shortening (e.g., Crisco) and two parts granulated
white sugar. Place shortening and sugar in a large container and mix by hand or with a mixer until well-blended.
Divide the paste-like mixture into hamburger-sized patties (about 1/4 lb.) on sheets of wax paper, and place one
patty per colony on the top bars in the middle of the broodnest. Grease patties work very slowly by protecting
young bees, which the mites prefer. Make sure the patties is on the top bars close to the brood nest, not on the
bottom board or on top of the honey supers. To keep tracheal mite levels from reaching damaging thresholds, it
is important to treat colonies from early fall through winter, and again in the early spring. Super colonies normally
as long as you are using plain patties (without antibiotics). Some beekeepers incorporate antibiotics (i.e. Terramycin®) into patties in the spring and/or fall as a foulbrood preventative. The antibiotic also may offer some advantage to colonies with varroa infestations or parasitic mite syndrome. Patties that include antibiotics (homemade or commercially-available) should be applied only when bees are not storing surplus honey (when colonies are not supered). Do not medicate bees when there is any danger of contaminating the honey crop, and always follow label instructions. |
Varroa Mite (Varroa jacobsoni) - (also
see Malady Info Overview - Varroa Mite) The varroa mite,
Varroa jacobsoni, is considered today by many to be the most serious malady of honey bees. It now occurs
nearly worldwide. (Click to view Map) This tick-like external parasite feeds on the
hemolymph (blood) of adult bees, larvae, and pupae. Heavy parasitism results in increased bee mortality and subsequent
weakening of the colony and can lead to colony death. The varroa mite is visible to the naked eye. The female mite is brown to reddish-brown in color, measuring 1.1 to 1.2 mm in length and 1.5 to 1.6 mm in width (about the size of a pinhead or a flea). Males are smaller, about 0.7 mm by 0.7 mm, and light tan in color. Adult males do not feed and are not found outside of brood cells. Adult female mites can live outside the brood cells and are also found on adult drone and worker bees. This behavior allows them to invade new host colonies of bees and survive the winter there. The flattened shape of the female's body makes it possible for the mite to hold onto a bee and move easily into the cells of developing bee brood. When on adult bees, female varroa are found mainly on the top of the bee's thorax at the point where the wings attach, between the head and the thorax, between the thorax and the abdomen, or between overlapping segments of the abdomen. These are places where the mites can easily use their piercing mouthparts to penetrate the exoskeleton of their host and gain access to the bee's hemolymph (blood). These are also places where mites are less likely to be removed by bees grooming each other. |
Varroa Mite Life Cycle When female mites are ready
to lay eggs, they move into brood cells containing young larvae just before the cells are capped. They go to the
bottom of the brood cells and immerse themselves in the remaining brood food. After the cells are capped and the
larvae have finished spinning cocoons, the mites start feeding on the larvae. They begin laying eggs approximately
three days after the cell has been capped. A fertilized female mite lays a total of 4 to 6 eggs. The adult female
and its immature offspring feed and develop on the bee as it matures. The mite life cycle consists of four developmental
stages: the egg, two eight-legged nymphal stages (protonymph and deutonymph), and the adult. The period from egg
to adult takes about 6 to 7 days for the female and 5 to 6 days for the male. Mating occurs in the brood cells
before the new adult females emerge. The adult males die after copulation since their mouth parts (chelicerae)
are modified for sperm transfer rather than feeding. The old female and the newly-fertilized female offspring remain
in the brood cell until the young bee emerges. The adult bee serves as an intermediate host and a means of transport
for these female mites. |
 Varroa mites have a definite
preference for drone brood. More mite offspring can mature during the longer development time (capped period) of
the drones. However, worker brood also is attacked. Queen brood is attacked only in cases of heavy infestation.
Female mites produced in the summer live 2 to 3 months, and those produced in the fall live 5 to 8 months. Without
bees and brood, the mites can survive no more than 5 days. They can, however, live in a comb with sealed brood
at 68°F for up to 30 days. We do not know precisely how varroa mites spread so rapidly. We do know that these
mites can be spread by the movement of honey bee colonies (migratory beekeeping), the shipment of queens and package
bees, and the movement of colonies for pollination rentals. Beekeepers probably spread an infestation from one
colony to another through normal apiary manipulations. Infestations also are spread as a result of drifting (especially
drifting drones) and swarming bees. |
Damage and Symptoms Individual developing
bees, if infested with one to two adult mites (and offspring), usually emerge without visible damage and are normal
in appearance. They may, however, suffer from malnutrition, blood loss, or disease. Individuals that are heavily-infested
with more than five adult mites (which can produce as many as 15 nymphs) usually become visibly crippled or die
in their cells without emerging. In addition to the loss of hemolymph, varroa mites are known to transmit a number
of pathogens including several viruses. When adult bees are infested with two or more mites, they become restless
and fly with difficulty. Their life span is generally shorter than unparasitized bees and they perform tasks poorly.
Recognizable symptoms of varroa infestation depends upon the number of mites in a colony. Low-level varroa infestations are difficult to detect. Medium- to high-level infestations may result in the appearance of a spotty brood pattern, as well as the presence of malformed worker and drone adults with deformed wings (may be associated with deformed wing virus) and small abdomens. Such bees are often unable to fly and can be seen crawling on the ground. Bees will uncap and throw out infested brood, which can sometimes be found at the hive entrance or on the ground in front. Parasitized larvae may appear to have small, pale or dark-reddish brown spots on their normally white bodies. Colonies become severely debilitated as mite populations reach extremely high levels at the end of the brood rearing season. |
| Detecting Varroa There are several methods for detecting a varroa mite infestation, including sampling by ether-roll, examining pupae, or by sticky boards. Ether-roll sample. The ether-roll technique is a quick, relatively easy sampling method to check for the presence of mites. Brush approximately 200 to 300 bees from the broodnest into an empty clear glass jar (about 2 inches bees). Take care not to collect the queen. Close the lid and tap the jar to knock the bees to the bottom. Add a 1- or 2-second squirt of an ether-based aerosol starter fluid (the type used to start cars in cold weather). The ether will kill the bees and cause the mites to fall off the adult bees. Shake the jar of bees hard for 15 to 20 seconds, then turn the jar on its side and gently roll it. If present, mites will adhere to the sticky film left on the sides of the jar. Light infestations may be missed by this method; include drones in the sample to increase the chances of detecting mites. If mote than 25 mites/300 bees are found, consider treating all your colonies. Examining drone pupae with an uncapping fork. Another technique is to examine brood for the presence of mites. Uncap and examine sealed brood, especially drone brood. Remove individual pupae with forceps to permit visual inspection. A faster technique utilizes an uncapping fork to remove up to 50 drone pupae for close  examination. A small 10X hand lens will help considerably in visualizing the mites. If more than 25% of the pupae have mites, consider treating. Sticky boards. Some varroa mites will naturally fall to the bottom board, either because they are dead or because they have been groomed off or fallen off bees. These mites can bee found in the debris under the brood frames. A piece of white cardboard placed on the bottom board for a few hours makes it easier to spot the mites in the debris. For a longer test period, the white cardboard should be covered with a piece of wire screen (8 mesh-per-inch hardware cloth) to prevent the bees from removing fallen mites. Space the screen 1/4 inch above the white cardboard by stapling continuous strips of corrugated cardboard around the edges. To aid in trapping mites, sticky materials such as petroleum jelly can be applied to the white cardboard; in these cases, you must use a screen to keep the bees from removing the jelly. If over 100 mites are seen on a sticky board after 24 hours, consider treating. |
 Treatment:Non-Chemical Methods of Reducing Varroa Populations Since varroa mites are up to 8 times more attracted to drone brood than worker brood, it is possible to reduce varroa populations by removing mite-infested drone brood. Frames of drone comb are inserted into colonies to trap varroa mites. After the queen has laid brood on the frame and the cells are capped, these frames are removed from the colony and frozen to kill the varroa and the brood. This is especially effective in the early spring when varroa are concentrated on small patches of drone brood. Varroa can also be trapped on sticky boards. Since some of the mites that fall to the bottom board are alive, trapping these and removing them from the colony on a regular basis can help to reduce varroa populations. A similar technique utilizes a screen bottom board (8 mesh-per-inch hardware cloth), which allows detached mites to fall completely out of the colony; again reducing the varroa population. |
Chemical Treatments  Apistan®, a
plastic strip impregnated with the miticide fluvalinate, has been used for varroa control in the United States
since 1988. These strips are used to deliver a contact pesticide, which means that the mites must come in contact
with the strips in order for the material to be effective. For this reason, the strips are hung vertically inside
the brood nest. Always read and follow all label instructions. Current label recommendations require that all honey
supers be removed before any chemical mite control treatment is applied. Leave the strips on the colonies for a
minimum of 6 weeks and a maximum of 8 weeks. The number of strips placed on a colony depends on the number of frames
of bees in each colony. Use one strip per five (or fewer) frames of bees; distribute the strips evenly throughout
the brood nest. Colonies are typically treated in late summer or early fall to improve winter survival. However, since varroa populations typically peak in August and September, we may need to consider treating colonies with Apistan earlier; during early spring (before the honey flow) or the summer dearth (spring honey removed, fall honey supers not yet placed on colonies). If necessary, supers can be reapplied immediately after the strips are removed from colonies. Destroy any honey left in the hive during treatment or use it as bee food. By knocking down the population earlier, we may better protect the bees from mites and virus through winter. Apistan strips should be used once and then discarded; they should not be re-used. Used strips cannot deliver the same dose of fluvalinate that new strips can. Treating with used strips can expose the mites to a sub-lethal (non-killing) dose of the pesticide. While used strips may kill some mites, they will not kill as many as new strips. The surviving mites will then reproduce. It is likely that many of their offspring will be resistant to fluvalinate even at the full dose. By reusing the strips we invite the mites to develop resistance to our chemicals more quickly. Note: In the fall of 1997, mites resistant to fluvalinate were detected in several commercial and sideline operations in Pennsylvania and around the U.S. We recommend that beekeepers who have Apistan-resistant mites (please consult your bee inspector) use an alternative chemical (as of 1999, coumaphos or formic acid) to control varroa. However, Apistan should still be effective in most hobby and sideline beekeeping operations. Coumaphos Strips In January 1999, coumaphos, a second chemical treatment for varroa mites was approved on a section 18 emergency-use basis. Beekeepers who have Apistan-resistant varroa mites (please consult your bee inspector) should switch to coumaphos for varroa mite control. Coumaphos is incorporated in a plastic strip which is sold under the brand names of "Bayer Bee Strips" or "CheckMite+ Strips". Coumaphos strips are hung between broodnest frames similar to Apistan strips. Treatment length is 45 days. Always read and follow all label instructions. Remove all surplus honey from hives before treatment. Note: Wear chemical-resistant gloves during applications and removals and use extreme care in handling this material; it can be absorbed through the skin. Formic Acid Gel Formic acid was also registered in the United States in 1999, for the control of both varroa and tracheal mites. Formic acid gel packs are applied to the top bars of the colony in late summer or early fall; one gel pack per colony. Formic acid works as a fumigant (vapor) and must evaporate from the packs to kill mites; this requires warm daytime temperatures and proximity to the heat from the bee cluster. The gel in the pack slows down and evens out the evaporation of the formic acid, making only one application necessary for a three-week treatment. Always read and follow all label instructions. Note: Wear chemical-resistant gloves during applications and removals and use extreme care in handling this material; formic acid is a strong acid which may cause burns to skin or upon inhalation. See Chemical Control for more information on mite control. |
Parasitic Mite Syndrome (PMS) - (also see
Malady Info Overview - PMS) Since the introduction
of mites, we have been seeing diseased bee larvae with symptoms resembling a cross between foulbrood and sacbrood.
The USDA Bee Research Lab has found these diseased larvae to be infected with one, or commonly several, viruses.
This condition seems to be limited to colonies infested with varroa mites. Additionally, beekeepers have had bees
disappear completely from previously healthy colonies in the early fall. This situation most likely is associated
with varroa mites, viruses, or a combination of both. This complex of symptoms has been given the name "Parasitic
Mite Syndrome" or PMS.Symptoms Affected larvae die in the late larval or prepupal stage, stretched out in their cells often with their heads slightly raised. In the early stage of infection, they are white but dull rather than glistening, and they look deflated. Later, the larva may have gray or brownish spots. Prepupa die after the cell has been capped, and the cappings may be perforated or completely removed by the bees. When the larval remains are stirred with a toothpick or small twig, they do not rope out but are globular (similar to European foulbrood) |
Virus Control and Treatment (PMS)  If the virus complex
is associated with mites, then controlling both varroa and tracheal mites is important in combating the viruses.
Because many infected colonies seem to collapse, or the bees seem to "disappear" in early fall, it is
necessary to control the mites well before this time. Although we do not understand why, treating varroa-infested
colonies with an antibiotic such as oxytetracycline (Terramycin) seems to help them survive and perform better.
Antibiotics are effective in treating bacterial diseases, such as European foulbrood, but are unlikely to have
a direct effect on the virus infections common with mite infestations. Even so, oxytetracycline treatments seem
to offer some advantage to colonies with mite infestations. Also, according to two years of survey results from
Pennsylvania, beekeepers treating varroa-mite-infested colonies in autumn with fumagillin significantly improved
colony winter survival. Fumagillin fed in syrup is used to suppress nosema disease in overwintered colonies and
newly established packages. Nosema disease weakens the digestive track of infected bees and may allow pathogens
to enter the honey bees gut where they can cause significant damage. Treating colonies in fall with Fumidil-B
might also improve their chances of survival. |